Voice-over-Internet protocol (“VoIP”) refers the transmission of voice data over a data network using the Internet protocol. For example, VoIP data may be transmitted via a wireless network, such as a WiMAX (“Worldwide Interoperability for Microwave Access”) network. WiMAX is based on the IEEE (Institute of Electrical and Electronics Engineers) standard 802.16-2001 and IEEE standard 802.16-2004, which may also be referred to as a Wireless Metropolitan Area Network (or WirelessMAN). WiMAX networks may typically be connected to the Internet, thereby providing wireless broadband Internet access to users.